By: John Axtell Posted at: 02/06/2018 11:51 PMGREEN RIVER, S.D. (AP) - Wyoming authorities say a 10-year-old Green River boy kept his sisters, ages 1 and 3, warm for nearly 4 hours in near-freezing temperatures in their crashed pickup early last Thursday after a single-vehicle accident on Interstate 80 near Lyman killed their mother and badly injured their father.

The Wyoming Highway Patrol says the accident involving the family of Samuel and Kymbrlee Smith occurred around 2:00 am, but the wreck wasn't reported until about 6:00 when a person driving by spotted the pickup and called 911.

The Highway Patrol says 30-year old Kymbrlee Smith was already dead when troopers arrived at the scene while 31-year Samuel Smith, the driver, was flown to the University of Utah Medical Center where he remains in critical but stable condition. The children were admitted to a nearby hospital and later released to family members.

The Patrol says the pickup drifted off the pavement and hit a post. When Smith tried to steer back onto the road, he hit a bridge guardrail and the pickup rolled over the edge of the bridge and fell onto a business road below, landing on its top.

Troopers say both parents suffered head trauma that left them unable to help their children, but the 10-year old helped keep his sisters warm. The girls were in child safety seats while their brother and parents were all wearing seat belts. The troopers investigating the accident list fatigue as the leading cause of the crash.

A GoFundMe page has been set up to help the Smith's offset the costs of emergency services after the crash, hospital care, physical therapy, funeral expenses, and long-term care for the children and their father.